Aircraft sextant



March 31. 1925.

F. L. HUNT ET'AL AIcRAFT SEXTANT Filed June 3. 192,1

2 Sheets-Sheet l March 31'. 1925.

AIRCRAFT sEx'r/m'r Filed June s'. 1921l 2 sheets-sheet a v l l Jn/wam y .MY-M [l M withdrawn from the handle as a unit. The invention also contemplates means for- Patented Mar. 31, 1925.

UNITED STATES "i 1,531,615 PATENT oFElcE.

FRANKLIN L. HUNT AND KARL H. BELT, WASHINGTON, DISTRIC'R 0F COLUMBIA:

AIRCRAFT SEXTANT.

Application filed .Tune 3, 1921. Serial No. 474,582.

To all 'whom t 'may conce/m:

Be it known that we, FRANKLIN L. HUNT and KARL H. BEIJ citizens of the United States, residing at 2Washington, District of Columbia, have invented certain new and useful Improvements in Aircraft Sextants, of which the following is a specification.

This invention relates to seXtants particularly adapted for use on aircraft of all kinds. While particularly adapted for aircraft purposes, it will become apparent4 as the description proceeds that the sextant may be used on marine vessels and other places as well-as on aircraft.

l' One ofthe main objects of the invention is to provide a hand instrument for the uses above indicated in which the parts are compactly arranged and assembled, the arrangement being roductive of a light instrument which may be readily and quickly manipulated by hand for the purpose of taking observations either in the day time. or at night time.

A further object of the invention is to provide means for compensating for temperature changes affecting the levelling bubble.

It is desirable to have a levelling bubble of a certain size in order to provide for accurate observations' and to that end we provide novel means for regulating the size of the bubble under varying temperatures.

`A further object of the invention is to provide a novel constructionv and arrangement of supporting handle by which the-sextant is held when in use, said handle being of 'hollow formation and containing a lamp energizing battery, resistance and a controlling rheostat therefor, thevbattery contact, contact springs, resistance and .controlling means therefor being assembled on an end cap of the handle so that said parts may be adjusting or setting theangle of the bubble mirror in primarily adjusting the instrument to give accurate readings; also means xfor adjusting the angle of the index mirror,

with the same object in view.

With the above and other-objects in view,

,the invention consists in the novel construction, combination and arrangement herein fully described, illustrated and claimed. A In the accom anying drawings- Fig. 1 is asi e elevation of the seXtant; Fig. 2 is a vertical; longitudinal section through the same looking in the opposite 'The sextant, which is designed to be supported by one hand and adjusted by 'the other, comprises, in the preferred embodiment thereof, oppositely varranged side plates 10 and l11 arranged in spaced relation to each other as shown in Fig. 3, sufficient space being left between said side plates to allow for the several elements hereinafter particularly referred to.

Between the side plates 10 and 11 there is mounted a sun glass 12, the same being support-ed by a binding screw 13 vby means of whichthe angle of the sun glass 12 may be adjusted., Adjacent to the sun glass 12 is a semi-transparent index mirror 14 having trunnions 15 extending through the plates 10 and 11.' One of the trunnions 15 has fast thereon a worm segment 16 which meshes with and is actuated by a Worm 17. The shaft 18 of said worm extends downwardlyl and has a micrometer screw 19 thereon which is graduated as shown to enable the angleof the index;mirror 14 to be accurately gaged. The worm segment 16 is also graduated as4 shown, for the, same purpose, the graduations ofthe worm segment and the micrometer screw being read in .conjunction with each other for the purpose stated. For use after dark, an electric lamp 20 is provided, the same being pivotally mounted at 21 on one of the side plates of the frame of the instrument and connected by iexible conductor 22 to la battery hereinafter described and arranged in a tubular handle 23 located at one side o-f the frame of the sextant and connected with such frame byr struts 24.

chamberBO containing a suitable Huid or the side of the handle 23 and adapted to c 0n`1h liquid by means of which a bubblel is tact with a spring terminal 57' screwed to formed in said chamber'. Ait one side of the a collar 58 on the stem 49 as shown in Fig.

bubble chamber there is a diaphragm cham- 4. It will now be seen that thed resistance, ber 32 which is always yin, communication battery contact, and the contact springs for with the chamber by'- means of a tubular the push buttons are all'assembled on and connection or hollow screw 33 as best shown supported by the end cap 48 so that when in Fig. 5. A liexible'diaphragm 34 is placed said capy is detached, all of -said parts lare in the chamber 32 in a medial position thereremoved therewith. Y This provides the necin and clamped between rings 35 and 36, essary degree of accessibilityto keep the the outer side of thie chamber 32 being closed parts just referred to in adjustment. An-

by a cap 37 through the center of which is other push button switch 59 extending threaded an adjusting screw 38 that bears through the side wall of the handle 23 conagainst the diaphragm 34 and enables the trois the lamp 2O above described. The latter to be distorted. By the means just dewiring of the two lamps hereinabove described, the amount of fluid or liquid in the scribed and the arrangement of the push chamber 30 may be changed or varied S0 aS 1 button switches and resistance is illustrated to regulate the size of the bubble 31, it beingin Fig. 6, enabling either or` both of saidv desirable to have a bubble of a certain size lamps to be energized as needed and also in order to render the readings more accuenabling more or less resistance to be thrown rate. The bubble is used for the kpurpose of ingo Jhe bubble lamp circuit. levelling the instrument simultaneously with In operating the instrument in the day sighting the sun during the day time or a time, the eye is placed approximately at the planet or star atnight.

Below the bubble chamberv 'there is arobserverlooks downwardly at an angle ranged-an angularly disposed bubble mirror through the'sun glass l2 and sees the sun 39 which is' supported within a cage 40 reflected on the index mirror 14. Simultal against springs 41,' said bubble mirror 39 vneously he sees the bubble 31 which is lrebeing adjustable by means of a plurality of 'lected and projected by the ,lens against ladjusting SCrGWS 42 3S ShOWIl.A in Fig. 2- the index mirror 14. The two images ofthe This enables the angle of the bubble mirrorl bubble .and the sun should coincide on the to be accurately set for the purpose of re- `index mirrorv14v before an accurate reading fiecting the bubble into a collimating lens is obtained. They are brought into coinci- 43 which is situated between said bubble dence by'a careful adjustment of the indexl mirror and the index mirror 14 hereinabove mirror by means of the micrometer screw referred to and the angle of which, as pre- 19. At night time when sighting on a star, viously described, is adjustable by means of for example, the eye is placed under the inthe micrometer screw 19. A flexible conrdex mirror, the observer looking upwardly,`

ductor 44 leads from the battery in the through the index mirror 14 and directly at handle 23 to the bubble lamp 26. Athe star. The mirror 14 is then adjusted by `The handle 23 is closed at one end by an means of the micrometer screw 19 until the end cap 45 having soldered thereto afcontact bubble 31 is reflected and projected against spring 46 for the battery 47 contained in the the bottom of the indexmirror soas to coinhandle. Cap 45 is detachable.' The` Aother eide with the image of the star as viewed end of' the handle 23 is also normally closed through the'index mirror. The instrument bya detachable cap1 48 and carriesa central, is particularly adapted for aircraft purthreaded stem 49 Contact 5.0which bears against the battery the manner above described although such 47. The handle 23 carries .a binding post use of the instrument is not limited to airv `carrying a resistance element 53, along sition of a ship or vvehicle of any kind. To which 1s shdable the resistance control further increase accurate read-ings the upper 51 fr the bubble lamp conductor 44 hereincraft, the instrument being adapted for navi? aving at its .extremity a poses as quick readings may be obtained in..

above described. Mounted upon and cargation purposes and, in fact, for any pur.-v

ried by the stem 49 isa resistance core 52 pose where it is necessary to locate the po-j Spring 0I' Contact 54p1"0'ded With all -0p face ofthe'glass or lens 60 which overliesJ120 eratlng, button 55.'l By thls means more 0r' the bubble .chamber may .be provided with less resistance may be thrown 111120 the bubble concentric circles engraved or otherwise lampclrcult for QIltIOlllIlg the degree 0f represented thereon vfor the purpose 'of more lllumination of sa1d lamp, this being necesaccurately centering the bubble 31. The bot- Sary in order that the brilliancy of the bubtom of the vbubble. chamber 30 is .also comble may not interfere with accurate observaposed of a wall or thickness lof glass as tions vby throwing too great a glare into the shown at 61 or may consist of a lens forming eye of the observer. vFor energizing the bub\ a complemental .part of .the upperwall or ble lamp We'employ a. bubble lamp push lens 60 of the bubble chamber as shown in button -56 shdable through an4 opening in Fig. 5.

We claim: named adjustment, a laterally arranged In a hand sextant for aircraft, a frame, handle for ,the 'instrument arranged at. the n sun glass, a levelling bubble, a vbubble mir opposite side of the frame, and manually ror, a bubble lens between the bubble and controlled means contained in said handle i said 1111'1'o1','an index mirror between the for energizing said lamps.. 15

bubble 'mirror and the sunA lass, a lens bel In testimony whereof we have aixed our tween the bubble mirror am? the index mir- SignatllIGS- ror, a bubble lamp, a micrometer screw ad-l' justment for the index mirror arranged at FRANKLIN L. HUNT.

10 one side of the frame, a lamp for the last KARLH. BEIJ. 

